15407( 3) - 01-Nov-2017 20:07:44 - [ 1] HUBBLE SPACE TELESCOPE OBSERVING PROGRAM 15407 Version: 3 Check-in Time: 01-Nov-2017 20:07:44 STScI Edit Number: 0 Title NUV Monitoring of a SNIa with Late-Onset CSM Interaction ------------------------------------------------------------------------------------ Type Cycle GO/DD 25 ------------------------------------------------------------------------------------ Investigators Contact? PI: Dr. Melissa Lynn Graham University of Washington Y CoI: Dr. Peter E. Nugent Lawrence Berkeley National Laboratory N CoI: Ms. Chelsea Harris University of California - Berkeley N CoI: Dr. Mark Sullivan University of Southampton N CoI: Dr. Kate Maguire Queen's University Belfast N CoI: Dr. Mathew Smith University of Southampton N CoI: Dr. Ken Shen University of California - Berkeley N CoI: Dr. Ori Dosovitz Fox Space Telescope Science Institute N CoI: Prof. Ariel Goobar Stockholm University N CoI: Dr. Patrick Kelly University of Minnesota - Twin Cities N CoI: Prof. Alex V. Filippenko University of California - Berkeley N ------------------------------------------------------------------------------------ Abstract We propose for Director's Discretionary Time to monitor the first-ever Type Ia supernova (SN Ia) found to be experiencing late-onset interaction between its ejecta and circumstellar material. Very few SNe Ia have been observed to interact with CSM, and always within a month or two of peak brightness, which indicates that their CSM was relatively nearby. Based on observations of time-varying and/or blueshifted sodium absorption, more distant CSM is predicted to exist in about 20% of all SN Ia systems, but has never been directly confirmed. This motivated our Cycle 24 Snapshot program to search for late-onset interaction in a sample of 80 nearby SNe Ia with NUV imaging at 1 to 3 years after exposion. In September 2017 we discovered PanSTARRS 15dpq to have a F275W apparent magnitude of 24.3 mag, ~2 years after its explosion. An optical spectrum in October 2017 showed a broad hydrogen emission line, confirming that the emission is associated with CSM interaction. At early-times, PS15dpq did not exhibit any sodium absorption or CSM interaction, making it the first and only example of SN Ia surrounded by a cleared-out inner volume and distant CSM. We propose for one epoch of STIS spectroscopy to constrain the NUV emission features (i.e., continuum- or line-emission), followed by six epochs of time-series NUV photometry to monitor the luminosity evolution. These data will allow us to place direct physical constraints on the amount and distribution of the CSM surrounding PS15dpq and will provide unique insight into the diversity of SN Ia progenitor systems, which is important because they are commonly used as standardizable candles for dark-energy cosmology. ------------------------------------------------------------------------------------ Observations Description ------------------------ A single visit, 5 orbit STIS spectrum of our target with the NUV-MAMA detector and the G230L grating. ------------------------------------------------------------------------------------ 15407( 3) - 01-Nov-2017 20:07:44 - [ 2] TARGET LIST Fixed Targets ------------------------------------------------------------------------------------------------------------------------------------ Tar| Target | Target | Target |Coord | Radial | Flux data No | Name | Description | Position |Eqnx | Vel. | ------------------------------------------------------------------------------------------------------------------------------------ 1 PS15DPQ EXT-STAR, SUPERNOVA RA=03H09M12.7380S +/- 0.3748", J2000 Z = V = 35 F275W 24.3 mag on 2017-09-12 TYPE IA DEC=+27D31'16.81" +/- 0.3748" 0.038 Reference Frame: ICRS Extended: NO Comments: This target is not used but kept for now in case we decide to go for direct acquisition. Epoch of Position RA proper motion (seconds of time/yr) DEC Proper Motion (arcsec/yr) Annual Parallax (arcsec) 2000.0 0.0 0.0 0.0 ------------------------------------------------------------------------------------------------------------------------------------ 2 SDSSJ030910. STAR, F0-F2 RA=03H09M10.6880S +/- 0.15", J2000 F275W 20.0 mag 69+273107.5 DEC=+27D31'7.45" +/- 0.15" Reference Frame: ICRS ------------------------------------------------------------------------------------------------------------------------------------ 3 PS15DPQ-AS-O EXT-STAR, SUPERNOVA RA-OFF=+2.05S, DEC-OFF=+9.3528", J2000 V = 35 F275W 24.3 mag on 2017-09-12 FFSET TYPE IA FROM 2 Comments: Same as target PS15DPQ, but with location defined in reference to star SDSSJ03... ------------------------------------------------------------------------------------------------------------------------------------ 15407( 3) - 01-Nov-2017 20:07:44 - [ 3] Visit: 01 Visit Requirements: PCS MODE FINE; SCHED 100%; BETWEEN 03-NOV-2017:00:00:00 AND 30-NOV-2017:00:00:00; ON HOLD ; TOO RESPONSE TIME 21.0D On Hold Comments: Would like to execute as soon as possible. Additional Comments: Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exp | Target | Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Num | Name | Config | Mode | or FOV |Element |Waveln.| Parameters |Exp| (Total) | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 1 SDSSJ030910 STIS/CCD ACQ F28X50LP MIRROR 1 2 S (2 S) .69+273107. 5 Comments: We are not entirely sure of this star's spectral type. I've used Pickles F2 since it appears quite blue. In our HST image it is F275W 20 mag, and in the SDSS photometry it has a ugriz of 17.0/15.2/14.3/16.4/13.7 mag. ------------------------------------------------------------------------------------------------------------------------------------ 2 PS15DPQ-AS- STIS/NUV ACCUM 52X0.5 G230L 2376 5 2720 S OFFSET -MAMA see below (12991 S) Comments: The object is PS15DPQ-OFFSET, whose coordinates are defined as offsets from star SDSSJ0... ------------------------------------------------------------------------------------------------------------------------------------ Sub Exposures ------------------------------------------------------------------------------------------------------------------------------------ Target | Exp |Instr | Oper. | Aper |Spectral|Cent.|Primary |Secondary |Iteration |CR-SPLIT |Orbit |Duration Name | Num |Config | Mode | or FOV |Element |Wave.|Pattern Pos |Pattern Pos |Num |Num |Number | ------------------------------------------------------------------------------------------------------------------------------------ SDSSJ030910.69+2731 1 STIS/CCD ACQ F28X50LP MIRROR none none none none 1 N/A 07.5 PS15DPQ-AS-OFFSET 2 STIS/NUV ACCUM 52X0.5 G230L 2376 none none 1 none 1 2108.0 S -MAMA PS15DPQ-AS-OFFSET 2 STIS/NUV ACCUM 52X0.5 G230L 2376 none none 2 none 2 2738.0 S -MAMA PS15DPQ-AS-OFFSET 2 STIS/NUV ACCUM 52X0.5 G230L 2376 none none 3 none 3 2715.0 S -MAMA PS15DPQ-AS-OFFSET 2 STIS/NUV ACCUM 52X0.5 G230L 2376 none none 4 none 4 2715.0 S -MAMA PS15DPQ-AS-OFFSET 2 STIS/NUV ACCUM 52X0.5 G230L 2376 none none 5 none 5 2715.0 S -MAMA 15407( 3) - 01-Nov-2017 20:07:44 - [ 4] Summary Form for Proposal 15407 Item Used in this proposal ------------------------------------------------------------------------------------------------------------------------------------ Apertures 52X0.5, F28X50LP ------------------------------------------------------------------------------------------------------------------------------------ Configurations STIS/CCD, STIS/NUV-MAMA ------------------------------------------------------------------------------------------------------------------------------------ Opmodes ACCUM, ACQ ------------------------------------------------------------------------------------------------------------------------------------ Optional Parameters ------------------------------------------------------------------------------------------------------------------------------------ Special Requirements BETWEEN 03-NOV-2017:00:00:00 AND 30-NOV-2017:00:00:00, ON HOLD , PCS MODE FINE, SCHED 100%, TOO RESPONSE TIME 21.0D ------------------------------------------------------------------------------------------------------------------------------------ Spectral Elements G230L, MIRROR ------------------------------------------------------------------------------------------------------------------------------------ Target Names PS15DPQ-AS-OFFSET, SDSSJ030910.69+273107.5 ------------------------------------------------------------------------------------------------------------------------------------